Electronic Thermometer

Electronic thermometers display either a predicted equilibrium temperature based on measurements taken over 15-30 seconds (in predictive mode) or an actual equilibrium temperature that is generally achieved in a minute or less (in continuous mode).

From: Physical Rehabilitation , 2007

Vital Signs

Brian K. Peterson , in Physical Rehabilitation, 2007

Electronic Thermometers.

Electronic thermometers detect temperature changes using a thermoresistive device in which the electrical resistance changes in response to changes in temperature ( Fig. 22-3). This device may be a thermistor or a thermocouple and is incorporated into the tip of a probe. Thermistors are very small and therefore respond rapidly to changes in temperature. 18 The current flow from a thermistor is translated into a temperature reading that is displayed on a digital readout. Electronic thermometers display either a predicted equilibrium temperature based on measurements taken over 15-30 seconds (in predictive mode) or an actual equilibrium temperature that is generally achieved in a minute or less (in continuous mode). 4

Electronic thermometers are relatively easy to use and measure temperatures from 31.6°-42.2° C in predictive mode and from 26.7°-42.2° C in continuous mode. 18 The low range available in continuous mode makes this device useful for measuring temperature in hypothermic patients. Electronic thermometers are portable and can be used to measure oral, axillary, and rectal temperatures. Axillary temperature is measured in the same way as with a mercury-in-glass thermometer but using the electronic probe and waiting for the signal to indicate that the temperature is ready on the digital display. There are separate color-coded probes for oral and rectal measurements, and the disposable probe cover needs to be in place to operate, which helps reduce the risk of cross-contamination. 1,18 An audible signal indicates when the temperature on the digital display is ready to be recorded.

Giuliano et al found that oral measurements using an electronic thermometer produced more accurate and reproducible measurements than tympanic thermometers and therefore recommend these be used when pulmonary artery catheter placement is not indicated. 17 Pugh-Davies et al found that although the average accuracy of oral temperature measures taken with mercury-in-glass and electronic thermometers were not significantly different, the electronic thermometers produced greater fluctuation of readings with up to 23% of electronic measurements differing by 0.5° C or more when only 6% of mercury-in-glass thermometer readings varied this much. 19

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Taking the Temperature

Dr. Anika Niambi Al-Shura BSc., MSOM, Ph.D , in Physical Examination in Cardiovascular Chinese Medicine, 2014

4.3 Part 3: Procedure

Copyright © 2014 Anika Niambi Al-Shura. Published by Elsevier Inc. All rights reserved.

4.3.1 Body Reading

A digital thermometer can be used in these places for adults: armpit or mouth. It may seem strange to take an armpit reading for an adult, but in many cases the reading will provide the same results as ear or mouth. The use of a glass or plastic digital thermometer should be a matter of hygienic, monitoring method or protocol preference.

4.3.2 Head Reading

An ear thermometer is instant and effective for detecting body temperature changes. For serious heart patients, an instant ear temperature reading is convenient enough to be taken at different time periods during the day, and more often according to condition:

Twice during both morning and afternoon for menopausal heart patients. This purpose is also connected with determining hot flashes.

Twice during night for patients with moderate to severe heart disease. This purpose is connected with increased symptoms during this time of the day.

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Temperature

Steven McGee MD , in Evidence-Based Physical Diagnosis (Fourth Edition), 2018

Both electronic thermometers (rectal, oral, axillary sites) and infrared thermometers (forehead and tympanic membrane) accurately measure body temperature, although variability is greatest with the tympanic thermometer. A temperature reading of 37.8°C or more using any of these instruments is abnormal and indicates fever.

The patient's subjective report of fever is usually accurate.

In patients with fever, the best predictors of bacteremia are the patient's underlying diseases (e.g., renal failure, hospitalization for trauma, and poor functional status all increase the probability of bacteremia). The presence of shaking chills also increases the probability of bacteremia. (A chill is shaking if the patient feels so cold that his or her body involuntarily shakes even under thick clothing or blanket.)

Although classic fever patterns remain diagnostic in certain infections (e.g., typhoid fever and tertian malaria), the greatest value of fever patterns today rests with their response to antimicrobial agents. Persistence of fever despite an appropriate antibiotic suggests superinfection, drug fever, abscess, or a noninfectious mimic of an infectious disease (e.g., vasculitis, tumor).

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Etiologic Agents of Infectious Diseases

Nalini Singh , David Y. Hyun , in Principles and Practice of Pediatric Infectious Diseases (Fourth Edition), 2012

Prevention

Meticulous hand hygiene with soap and water should be performed before and after donning gloves when any contact is expected with patients infected with C. difficile. All healthcare personnel (HCP) should use glove and gown precautions when in contact with the patient and the surrounding environment. 58,59 Waterless gel is ineffective in killing spores of C. difficile. Cases of HA-CDAD in HCP have occurred. Children with CDAD should not attend out-of-home childcare facilities while symptomatic with diarrhea.

Environmental contamination plays an important role in the transmission of C. difficile. 28 C. difficile has been transmitted via electronic thermometers. 60 Endoscopes have not been implicated in C. difficile transmission. The degree to which the environment becomes contaminated is proportionate to the severity of disease in the patient. Diluted sodium hypochlorite successfully eradicates spores whereas routine hospital cleaning agents such as quaternary ammonium compounds are ineffective. Vaporized hydrogen peroxide delivered via a special apparatus is successful in reducing environmental contamination of C. difficile. 61 This procedure can be carried out in vacant hospital rooms and requires that the room be sealed off to ensure efficacy and avoid inadvertent exposure to patients. The effectiveness of this new technology needs further evaluation. Antimicrobial stewardship programs promoting judicious use of antimicrobial agents can also reduce the risk of CDAD. 62

Key Points.

Diagnosis and Management of Clostridium difficile Infection

Epidemiology

Acquired from infected individuals or contaminated environments, especially healthcare environments

Evolving from healthcare-associated to community-acquired disease

Exposure to antibiotic therapy is a risk factor for developing disease

Neonates can be colonized without symptomatic illness

Clinical Features

Most commonly manifests as mild to moderate diarrhea with or without mucous or blood in stool

Pseudomembranous colitis

Complications include toxic megacolon, intestinal perforation, sepsis, ascites, intussusception, and pneumatosis

Diagnosis

Detection of C. difficile toxins

Enzyme immunoassay (EIA) kits for toxins A and B

Cell culture cytotoxicity assay is gold standard but associated with high cost and slow turnaround time

Culture isolation of C. difficile cannot distinguish between toxigenic and nonpathogenic colonizing strains

Two-step identification of organism's glutamate-dehydrogenase (GDH) antigen, followed by EIA toxin assay if GDH positive, holds promise because of rapidity and high predictive values

Treatment

Discontinuation of precipitating antibiotic

Initial infection:

Mild to moderate disease: oral metronidazole (30 mg/kg/day in 4 divided doses, max. 2 g/day)

Severe disease in patients who have underlying intestinal disease, or are unresponsive to metronidazole therapy, or are critically ill: oral vancomycin (40 mg/kg/day in 4 divided doses, max. 125 mg/dose)

Severe disease with shock, ileus, or megacolon: oral vancomycin and intravenous metronidazole

Duration of therapy is minimum of 10 days

Relapse infection:

First relapse: same regimen as the initial episode

Second or later relapse: oral vancomycin in therapeutic and then tapered or pulsed therapy

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Clostridium difficile

Nalini Singh , Karl Klontz , in Principles and Practice of Pediatric Infectious Diseases (Fifth Edition), 2018

Prevention

Meticulous hand hygiene with soap and water should be performed before and after donning gloves when any contact is expected with patients infected with C. difficile. All healthcare personnel should use glove and gown precautions when in contact with the patient and the surrounding environment. 61,62 Waterless gel is ineffective in killing spores of C. difficile. Cases of healthcare-associated CDAD in healthcare personnel have occurred. Children with CDAD should not attend out-of-home childcare facilities while symptomatic with diarrhea.

Environmental contamination plays an important role in the transmission of C. difficile. 28 C. difficile has been transmitted through electronic thermometers. 63 Endoscopes have not been implicated in C. difficile transmission. The degree to which the environment becomes contaminated is proportionate to the patient's severity of disease. Diluted sodium hypochlorite successfully eradicates spores, whereas routine hospital cleaning agents such as quaternary ammonium compounds are ineffective. Vaporized hydrogen peroxide delivered through a special apparatus is successful in reducing environmental contamination of C. difficile. 64 This procedure can be carried out in vacant hospital rooms and requires that the room be sealed off to ensure efficacy and avoid inadvertent exposure to patients. The effectiveness of this technology needs further evaluation. Comprehensive strategies to prevent C. difficile that include antimicrobial stewardship have been published. 65 A promising first-in-human phase 1 vaccine trial in adults using toxoid antigens was published in 2016. 66

Key Points

Diagnosis and Management of Clostridium difficile Infection

Epidemiology

Acquired from infected people or contaminated environments, especially healthcare environments

Evolving from healthcare-associated to community-acquired infection

Exposure to antibiotic therapy a risk factor for developing disease

Neonates can be colonized without symptomatic illness.

Clinical Features

Most commonly manifesting as mild to moderate diarrhea with or without mucus or blood in stool

Pseudomembranous colitis

Complications including toxic megacolon, intestinal perforation, sepsis, ascites, intussusception, and pneumatosis intestinalis

Diagnosis

Detection of C. difficile toxins

Two-step enzyme immunoassay first to detect glutamate dehydrogenase (sensitive but nonspecific) and then to detect toxin if step 1 is positive

Stand-alone nucleic acid amplification test

Treatment

Discontinuation of precipitating antibiotic

Initial infection:

Mild to moderate disease: oral metronidazole 30 mg/kg/day in 4 divided doses, maximum 2 g/day

Severe disease, as in patients who are in an intensive care unit, have proven pseudomembranous colitis, have underlying intestinal disease, or are unresponsive to metronidazole therapy: oral vancomycin 40 mg/kg/day in 4 divided doses, maximum 2 g/day

Severe disease with shock, ileus, or megacolon: vancomycin enema and intravenous metronidazole

Duration of therapy a minimum of 10 days

Relapse infection:

First relapse: same regimen as the initial episode

Second or later relapse: oral vancomycin in therapeutic and then tapered or pulsed therapy are recommended. Metronidazole should not be used for treatment of a second recurrence because neurotoxicity is possible.

Fidaxomicin approved for treatment in adults

All references are available online at www.expertconsult.com .

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Handbook of Pharmaceutical Analysis by HPLC

Wilhad M. Reuter , in Separation Science and Technology, 2005

Temperature accuracy

To test for temperature accuracy of a column oven, one should place the temperature probe/sensor of a calibrated/verified electronic thermometer (with at least 0.5°C precision) into the oven. The probe/sensor should not make contact with anything inside the oven. With the oven door closed, allow the temperature to stabilize for at least 20 min at each tested temperature (e.g., 30, 45 and 60°C). The thermometer's temperature should then be recorded at each temperature. The difference between the actual and set temperature should typically be within ± 1°C.

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Button Batteries

T Litovitz , in Encyclopedia of Toxicology (Third Edition), 2014

Uses

Button batteries are ubiquitous. They are used as a power source for hearing aids, games and toys, watches, cameras, calculators, media players, remote controls, key fobs, digital thermometers, lighted jewelry, musical or talking books, singing greeting cards, phones, monitors, medical equipment including medication pumps, garage door openers, penlights, clocks, dog collars, flameless candles, flashing or musical shoes or other fashion accessories, musical instruments, baby monitors, and a variety of other household products. Most button cells range in diameter from 5.8 to 23 mm, with four sizes accounting for 95% of ingested cells including 11.6 mm, 7.9 mm, 20 mm, and 5.8 mm (in decreasing frequency order). The chemistry of ingested button cells, in decreasing frequency order, is either manganese dioxide (alkaline), zinc-air, lithium, or silver oxide. Since the 1996 enactment of the US Mercury-Containing and Rechargeable Battery Management Act, mercuric oxide button batteries are no longer marketed; other types of button cells do not contain clinically significant amounts of mercury.

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Clinical Engineering in an Academic Medical Center

Ira Soller , in Clinical Engineering Handbook, 2004

Device Responsibility

SMIC is responsible for approximately 10,000 active medical devices. The number changes daily as new equipment is acquired and older equipment is retired from service. The equipment runs the gamut from simple electronic thermometers to sophisticated ultrasound imaging systems, located throughout the institution. To bring order to this vast array of medical equipment and to simplify the gathering and distribution of data relating to these medical devices, SMIC follows the medical device classification nomenclature found in Health Devices Sourcebook and Medical Device Register. At present, 500 different equipment nomenclatures are used to describe this equipment, the large number suggesting the breadth of knowledge that SMIC staff must have.

SMIC's mandate does not include X-ray or ionizing radiation devices, which are managed by the Radiation Physics Department, nor devices such as stretchers, hospital beds, and wheelchairs, which are maintained by the Facilities Management and Development Department.

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Thermoregulation: From Basic Neuroscience to Clinical Neurology, Part II

Charmaine Childs , in Handbook of Clinical Neurology, 2018

Digital thermometers

With the demise of the mercury-in-glass thermometer in routine clinical care on safety grounds, new types of thermometer have come to the forefront of modern thermometry. The most well recognized in routine practice is the hand-held digital thermometer. Other types of digital temperature-monitoring systems are incorporated into dedicated bedside temperature-monitoring systems at individual bed spaces of the intensive care and high dependency units or in portable standalone patient-monitoring systems, as used in the ambulance service.

Temperature probes and monitoring systems of the type used in critical care or anesthesia where the sensor per se is placed and fixed in situ within the body (e.g., esophagus, pulmonary artery, brain ventricle, and brain white matter) usually have the temperature sensor housed within the tip of the sensor element (implantable probe). The probe may be constructed for a single parameter (temperature) or, as in the newer, advanced monitoring systems, there may be two or more measurement parameters. For example, the multiparameter sensors available commercially for neurocritical care (Fig. 29.4) provide a temporal profile of multiple parameters, one example being temperature, pressure, and brain tissue oxygen content.

Fig. 29.4

Fig. 29.4. Multiparameter intracerebral measurements in a patient with severe traumatic brain injury (TBI) undergoing invasive brain monitoring. Changes in deep white-matter temperature (Tti), ventricular temperature (TbrV), and rectal temperature (Trec) show the correspondence between the brain and core body sites over the course of 190 hours from injury. Changes in brain tissue oxygen content show that tissue oxygen (mmHg) follows a similar pattern of brain and body temperature which in this patient suggests low tissue content commensurate with hypoxia.

(Childs, unpublished data.)

Other options include multiple tissue chemistry in a single probe and, if additional probes are used, a complete profile of chemistry, temperature, pressure, and oxygen content can give the clinician a detailed profile of the physiologic and pathophysiologic changes occurring in the injured tissue. These sensors have been shown to be reliable over an extended period of neuromonitoring (Childs et al., 2014).

Figure 29.4 illustrates the value of multiple measurement parameters providing information to the clinician and shows, in this example, the correspondence in temperature at two brain sites. It also shows the near exact measurements obtained using a rectal probe and refutes the often-reported lag in temperature between rectal values and other core temperatures, indicating that rectal temperature, in the main, provides a reliable and reproducible surrogate for brain temperature where insertion of sensors in the brain is justifiable clinically (Childs et al., 2005).

The type of sensor used at the tip of the temperature measurement probe (or in dedicated hand-held thermometers) falls broadly to two types: thermocouple or thermistor. A third digital thermometer type, the resistance temperature detector, usually using platinum as the resistance metal (platinum resistance thermometer), is more often used in the laboratory for calibration of thermistors and thermocouples. Platinum resistance thermometers are stable over long periods, and are the most accurate sensors, especially in industrial applications. Platinum resistance thermometers cover a temperature range of –200o to 800oC (http://www.Enercorp.com/temp/Thermistors_comparison). They have a fast response time (Mangum et al., 2001). The disadvantage is in their cost.

In the clinic it is not obvious, looking at a thermometer or bedside device, to know the type of measurement sensor without first checking the product information sheet, for temperature sensors may be engineered using a thermocouple or thermistor (HMSO, 1981).

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Charting the menstrual cycle

Jane Lyttleton BSc (Hons) (NZ) MPhil (UK) Dip TCM (Aus) Cert Acup (China) Cert Herbal Med (China) , in Treatment of Infertility with Chinese Medicine (Second Edition), 2013

The thermometer

In the case of recording and comparing changes in the resting or basal temperature of the body a reliable thermometer is needed – the change is a subtle fluctuation and not one which can be discerned subjectively, as can fever. A mercury or digital thermometer can be used. Digital thermometers are a little easier to read, especially in those groggy first few minutes of the day just after waking, but they are more expensive than the mercury type, and they can be slightly less accurate (although this is not usually a problem for our purposes). It is possible to buy a mercury thermometer designed to measure only the basal body temperature (called a basal body temperature thermometer). In this case the scale covers a narrower range than usual and the gradations are more spread out and easier to read than on a regular thermometer. However, most women use the regular thermometer normally kept in the bathroom cupboard for measuring fevers. Now, however, the thermometer will be kept on the bedside table.

On waking in the morning, after at the very least 3   h uninterrupted sleep, the thermometer is placed in the mouth and left for 3–5   min. BBT can also be measured by placing the thermometer in the vagina or rectum. Because these routes are slightly less convenient, they are less often used. However, if we are finding that the temperature readings are very erratic and it is hard to determine a pattern, then I sometimes recommend the vaginal route, which can give a more stable pattern.

The thermometer is removed, the temperature reading taken and its value noted on the chart under the correct day and date. For a mercury thermometer, it can be placed carefully on the bedside table and the reading taken some time later in the morning or even when going to bed the next evening. This is because most mercury thermometers will remain stable at the temperature they have reached until the mercury is given a firm shake down with a sharp flick of the wrist. After reading and recording the temperature, the mercury in the thermometer should be returned to its base level and the thermometer wiped clean ready for the next morning's use.

It is important that the temperature is read at roughly the same time each morning, because later waking raises the basal body temperature. Thus, a very erratic-looking chart may reflect nothing more than a rather erratic sleep and waking pattern. Some studies have shown that the basal temperature rises 0.09°C for each hour of delayed rising in the morning. 6 Thus, BBT charts can be adjusted for different waking times by moving the recorded temperature one square up or down for each hour of waking earlier or later than usual.

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